In the field of electrical heating it has always been desirable to control the electrical energy going to the heating element so that (1) the heat remains constant for any given assignment and (2) the control circuit element or control circuit elements do not "burn out" by current overloading. In the past thermocouples or other separate temperature sensors have been employed extensively to measure the temperature at the heating element location and thus provide control signals to control the input electrical energy to the heating element. In the U.S. Pat. No. 3,679,871 a circuit is described which provides that the heating element is designed to act as a temperature sensor. The last mentioned circuit is designed so that as the temperature of the heating element increases (and therefore its resistance becomes higher) the difference in voltage across the bridge mid-points changes accordingly and a signal to the control circuitry connected across the bridge is provided. This arrangement permits the system to decrease the amount of current going to the heating element circuit and alternatively to increase the amount of current going to the heating element circuit depending upon the resistance value of the heating element. The circuit of U.S. Pat. No. 3,679,871 functions quite well but does have some drawbacks in that: it employs two silicon controlled rectifiers (SCR's) to effect the bidirectional current flow; it does not provide for protecting the main triac, or the two silicon controlled rectifiers or other circuit elements if there is an over current condition, such as a short circuit, at the heating element circuit; and it does not provide for a "soft start", i.e. a means for permitting the heating element circuit to gradually "warm up" during the initial start up. The "soft start" limits surges of power that normally occur during cold start of PTC elements. It also prevents early degradation of the heating element and reduces short circuit conditions which result from crystalline distortion due to quick temperature changes in the heating element circuitry.